I'm probably wrong about this, but I always put down stupid stuff like this to young engineers who don't understand the ramifications of what they're doing.

Like back in the IR-only days, when Samsung TVs didn't yet have discrete input commands. A series came out that did not switch to TV when you'd hit channel up. At that time, we needed some command, any command, that would always go to some particular input. Usually we'd hit channel up -- the TV would go to TV reception -- then INPUT as many times as needed to get to the input we wanted. A dumb answer, but one that was simple to implement in a remote macro. This was taken away in that series. Instead of changing to the TV tuner, you'd get the message "That function is not available here."

If it consistently works this way, you might have to accept that it just won't do what you want it to do, and go with RS232, as you suggest.

Is there any other command that will turn it on? Again, for remote control macros, we'd sometimes have to send OPEN then PLAY to a DVD player because these were the only commands that would always turn it on and never turn it off.